In-plane switching mode liquid crystal display device and method for fabricating the same

ABSTRACT

An in-plane switching mode liquid crystal display (LCD) device, which reduces loss in transmittance and improves reflectance, and a method for fabricating the same are disclosed. The in-plane switching mode LCD device includes gate and data lines orthogonally crossing each other on a first substrate to define pixel regions having reflection portions and transmission portions; thin film transistors formed at the crossing of the gate and data lines; common electrodes formed at the transmission portions of the pixel regions; reflection electrodes formed at the reflection portions of the pixel regions; pixel electrodes formed parallel with the common electrodes at the transmission portions and formed above the reflection electrodes at the reflection portions; a second substrate facing and attached to the first substrate; a liquid crystal layer interposed between the first and second substrates; and first and second polarizing films respectively attached to outer surfaces of the first and second substrates.

This application claims the benefit of Korean Patent Application No.10-2004-0114832, filed on Dec. 29, 2004, which is hereby incorporated byreference as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an in-plane switching mode liquidcrystal display device and a method for fabricating the same, and moreparticularly to an in-plane switching mode liquid crystal displaydevice, which reduces loss in transmittance and improves reflectance,and a method for fabricating the same.

2. Discussion of the Related Art

A liquid crystal display (LCD) device, one type of flat display devicethat is receiving a great deal of public attention, changes opticalanisotropy by applying electric fields to liquid crystal having bothfluidity of liquid and optical characteristics of crystal. Compared to arelated art cathode ray tube, the LCD device has a lower powerconsumption rate and a small volume and is produced into a large-sizeand high-definition unit, thus being widely used.

Such a liquid crystal device has a structure in which a color filterarray substrate serving as an upper substrate and a thin film transistor(TFT) array substrate serving as a lower substrate face each other andliquid crystal having dielectric anisotropy is interposed between thetwo substrates. The liquid crystal display device is driven such thatTFTs attached to several hundreds of thousands pixels are switched onand off through address lines for selecting the pixels and a voltage isapplied to the corresponding pixels.

The liquid crystal display devices are driven in various modes accordingto characteristics of liquid crystal and structures of a pattern.

Specifically, there are a twisted nematic (TN) mode, a multi-domainmode, an optically compensated birefringence (OCB) mode, and an in-planeswitching mode. In the TN mode, liquid crystal directors are twisted atan angle of 90°, and a voltage is applied to the liquid crystaldirectors so that the liquid crystal directors can be controlled. In themulti-domain mode, one pixel is divided into several domains, and mainvisual field angles of the domains have different directions, therebyimplementing a wide visual field angle. In the OCB mode, a compensatingfilm is attached to a substrate so as to compensate for the variation inphase of light according to travel directions of the light. In thein-plane switching mode, two electrodes are formed on one substrate suchthat liquid crystal directors are twisted on the parallel planes oforientation films.

The liquid crystal display devices are divided into transmissible liquidcrystal display devices using a backlight as a light source, reflectiveliquid crystal display devices using external natural light as a lightsource, and semi-transmissible light crystal display devices proposed toovercome drawbacks of the transmissible and reflective liquid crystaldisplay devices, such as a high power consumption rate of thetransmissible liquid crystal display devices due to use of the backlightand a difficulty of using the reflective liquid crystal display deviceswhen the external natural light has a poor brightness.

The above-mentioned semi-transmissible light crystal display devicesimultaneously has reflection portions and transmission portions in unitpixels, thus interchangeably serving as reflective and transmissiblelight crystal display devices as occasion demands.

Transmission portions of the transmissible and semi-transmissible lightcrystal display devices cause light emitted from the backlight through alower substrate to be incident upon a liquid crystal layer to increaseluminance, and reflection portions of the reflective andsemi-transmissible light crystal display devices reflect the externalnatural light incident through an upper substrate, when the externalnatural light has a high brightness, to increase luminance.

Here, in order to respectively maximize the efficiency of the reflectionand transmission portions, a dual cell gap structure, in which the cellgap of the transmission portions is approximately twice that of thereflection portions, has been proposed.

A method for applying a semi-transmission mode in-plane switching modeliquid crystal display device is proposed. In this case, electrodes ofthe liquid crystal display device are configured in the dual cell gapstructure, thereby maximizing the efficiency of the semi-transmissionmode.

Hereinafter, with reference to accompanying drawings, an in-planeswitching mode liquid crystal display device employing thesemi-transmission mode will be described.

FIG. 1 is a plan view of a related art in-plane switching mode liquidcrystal display device, and FIG. 2 is a sectional view taken along lineI-I′ of FIG. 1.

The in-plane switching mode liquid crystal display device having pixelregions, each divided into reflection portions (R) and a transmissionportion (T), as shown in FIGS. 1 and 2, comprises a TFT array substrate11 having a plurality of lines and TFTs, a color filter array substrate21 facing the TFT array substrate 11, and a liquid crystal layer 31interposed between the substrates 11 and 21. The liquid crystal displaydevice employs a dual cell gap structure in which the cell gap of theliquid crystal layer 31 at the transmission portions (T) is twice thatof the liquid crystal layer 31 at the reflection portion (R).

Specifically, the TFT array substrate 11 comprises gate lines 12 anddata lines 15 orthogonally crossing each other to define pixel regions,TFTs obtained by laminating gate electrodes 12 a, a gate insulatinglayer 13, a semiconductor layer 14 and source/drain electrodes 15 a and15 b at the crossing of the two lines 12 and 15, reflection electrodes60 formed at the reflection portions (R) for reflecting external light,a passivation layer 16 formed on the data lines 15 and the reflectionelectrodes 60, and common electrodes 24 and pixel electrodes 17 crossingeach other on the passivation layer 16 for generating transversalelectric fields.

While the gate insulating layer 13 and the passivation layer 16 at thereflection portions (R) remain, the gate insulating layer 13 and thepassivation layer 16 at the transmission portions (T) are removed,thereby forming a dual cell gap structure. Since the total sum of thethicknesses of the removed gate insulating layer 13 and passivationlayer 16 is equal to that of the liquid crystal layer 31, the liquidcrystal cell gap at the transmission portions (T) is twice the liquidcrystal cell gap at the reflection portions (R).

As mentioned above, the cell gap (d1) at the transmission portions (T)and the cell gap (d2) at the reflection portions (R) is in the ratio ofapproximately 2 to 1. Thereby, ON/OFF modes of the transmission portions(T) and the reflection portions (R) are matched with each other.

Specifically, light incident upon the reflection portions (R) and lightincident upon the transmission portions (T) simultaneously reach thesurface of a screen. Natural light incident from the outside upon thereflection portions (R) reciprocates in the liquid crystal layer 31 andreaches the surface of the screen, and light incident from a backlightupon the transmission portions (T) passes through the liquid crystallayer 31 at the transmission portions (T) having a cell gap twice thatof the liquid crystal layer 31 at the reflection portions (R) andreaches the surface of the screen. Accordingly, the above two lightssimultaneously reach the surface of the screen.

The reflection electrodes 60 are made of Al, Al alloy, or Ag, andreflect light incident from an external light source, thereby displayingan image on the screen.

In the above device having the dual cell gap structure at the reflectionand transmission portions (R and T), the common electrodes 24 and thepixel electrodes 17 are disposed in parallel at both edges of thetransmission portions (T) without the passivation layer 16 and thereflection portions (R) with the passivation layer 16, therebyrespectively forming first transversal electric fields (E1) and secondtransversal electric fields (E2). Specifically, the first transversalelectric fields (E1) are formed throughout the cell gap (d1) of thetransmission portions (T) by the interaction between the first commonelectrode 24 a and the first pixel electrode 17 a and the interactionbetween the second common electrode 24 b and the second pixel electrode17 b, and the second transversal electric fields (E2) are formedthroughout the cell gap (d2) of the reflection portions (R) by theinteraction between the first pixel electrode 17 a and the second commonelectrode 24 b and the interaction between the second pixel electrode 17b and the first common electrode 24 a.

When an external light source is not present, the liquid crystal displaydevice is driven in a transmission mode by the first transversalelectric fields (E1) formed at the transmission portions (T), and whenan external light source is present, the liquid crystal display deviceis driven in a reflection mode by the second transversal electric fields(E2) formed at the reflection portions (R).

Widths of the transmission portions (T) and the reflection portions (R)are varied according to the size of the liquid crystal display device,which is substantially manufactured, or the number of pixels of theliquid crystal display device. In consideration of the transmittance ofthe liquid crystal display device, preferably, the widths of thetransmission portions (T) and the reflection portions (R) are in theratio of 1:1 to 3:1.

The color filter array substrate 21 comprises black matrices 22 forpreventing light leakage, and a color filter film 23 formed between theblack matrices 22.

For reference, although not shown in the drawings, the liquid crystaldisplay device further comprises orientation films attached to innersurfaces of the two substrates 11 and 21 for arranging molecules of theliquid crystal layer 31 in a designated direction, polarizing filmsattached to outer surfaces of the two substrates 11 and 21 forcontrolling an optical axis of light, and a phase contrast plateinterposed between the color filter array substrate 21 and thepolarizing film for delaying a phase difference.

The above-mentioned related art in-plane switching mode liquid crystaldisplay device has a problem, as follows.

When each of the reflection electrodes made of metal is disposed betweenthe corresponding common electrodes and pixel electrodes, the reflectionelectrodes distort the transversal electric fields generated between thecommon electrode and the pixel electrode, thereby causing a difficultyin arranging liquid crystal molecules in a desired direction.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to an in-plane switchingmode liquid crystal display device in which a Vcom signal is applied toreflection electrodes and pixel electrodes are additionally formed abovethe reflection electrodes so that liquid crystal molecules above thereflection electrodes can be arranged in a desired orientation bytransversalelectric fields, each generated between the reflectionelectrode and the pixel electrode, to have improved reflectance, and amethod for fabricating the same.

Additional advantages and features of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription or may be learned from practice of the invention. Theobjectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described herein, an in-planeswitching mode liquid crystal display device comprises gate lines anddata lines orthogonally crossing each other on a first substrate fordefining pixel regions having reflection portions and transmissionportions; thin film transistors at the crossings of the gate lines andthe data lines; common electrodes formed at the transmission portions ofthe pixel regions; reflection electrodes formed at the reflectionportions of the pixel regions; pixel electrodes formed parallel with thecommon electrodes at the transmission portions and formed above thereflection electrodes at the reflection portions; a second substrateattached to the first substrate; a liquid crystal layer interposedbetween the first and second substrates; and first and second polarizingfilms respectively attached to outer surfaces of the first and secondsubstrates.

In another aspect of the present invention, there is provided a methodfor fabricating an in-plane switching mode liquid crystal display devicecomprising: forming gate lines on a first substrate; forming a gateinsulating layer on the overall surface of the first substrate includingthe gate lines; forming data lines crossing the gate lines for definingpixel regions that are divided into reflection portions and transmissionportions; forming thin film transistors at the crossings of the gatelines and the data lines; forming common electrodes at the transmissionportions of the pixel regions; forming reflection electrodes formed atthe reflection portions of the pixel regions; forming a passivationlayer on the overall surface of the first substrate including thereflection electrodes; forming pixel electrodes on the passivation layerparallel with the common electrodes and pixel electrodes overlappingwith the reflection electrodes; attaching a second substrate to thefirst substrate, and forming a liquid crystal layer therebetween; andattaching first and second polarizing films respectively to outersurfaces of the first and second substrates.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a plan view of a related art in-plane switching mode liquidcrystal display device;

FIG. 2 is a sectional view taken along line I-I′ of FIG. 1;

FIG. 3 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a first embodiment of the presentinvention;

FIG. 4 is a sectional view taken along line II-II′ of FIG. 3;

FIG. 5 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a second embodiment of the presentinvention;

FIG. 6 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a third embodiment of the presentinvention;

FIGS. 7A to 7D are sectional views taken along line III-III′ of FIG. 3,illustrating a process for fabricating the liquid crystal display deviceof FIG. 3;

FIG. 8 is a schematic view of an optical system of the liquid crystaldisplay device of the present invention;

FIG. 9 is a table illustrating the variation in the polarized state ofreflection portions of the liquid crystal display device of the presentinvention;

FIG. 10 is a table illustrating the variation in the polarized state oftransmission portions of the liquid crystal display device of thepresent invention;

FIG. 11 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a fourth embodiment of the presentinvention;

FIG. 12 is a sectional view taken along line IV-IV′ of FIG. 11;

FIGS. 13A to 13D are sectional views taken along line V-V′ of FIG. 11,illustrating a process for fabricating the liquid crystal display deviceof FIG. 1; and

FIG. 14 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a fifth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 3 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a first embodiment of the presentinvention, and FIG. 4 is a sectional view taken along line II-II′ ofFIG. 3.

FIG. 5 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a second embodiment of the presentinvention, and FIG. 6 is a plan view of an in-plane switching modeliquid crystal display device in accordance with a third embodiment ofthe present invention.

The in-plane switching mode liquid crystal display device of the presentinvention is divided into reflection portions (R) corresponding to edgesof pixel regions and transmission portions (T) corresponding to innerparts of the pixels regions. The liquid crystal display device comprisesa TFT array substrate 111, a color filter array substrate 121, and aliquid crystal layer 131 having a dual cell gap structure interposedbetween the two substrates 111 and 121.

As shown in FIGS. 3 and 4, the TFT array substrate 111 comprises gatelines 112 and data lines 115 orthogonally crossing each other fordefining unit pixel regions, a gate insulating layer 113 laminatingbetween them for insulating the gate and data lines 112 and 115 fromeach other, TFTs formed at the crossings of the gate and data lines 112and 115, an organic insulating layer 116 and reflection electrodes 120formed at the edges of the pixel regions (hereinafter, referred to as“the reflection portions”), common electrodes 124 formed at the innerparts of the pixel regions (hereinafter, referred to as “thetransmission portions”), pixel electrodes 117 formed at the reflectionand transmission portions, and a passivation layer 118 formed on theoverall surface of the TFT array substrate 111 including the reflectionelectrodes 120 for insulating the pixel electrodes 117 from thereflection and common electrodes 120 and 124.

The color filter array substrate 121 having black matrices 122 and acolor filter layer 123 is attached to the TFT array substrate 111 suchthat the two substrates 121 and 111 face each other, and the liquidcrystal layer 131 is interposed between the two substrates 121 and 111.First and second polarizing films 150 and 151 are respectively attachedto outer surfaces of the two substrates 111 and 121. A compensating film160 is interposed between the TFT array substrate 111 and the firstpolarizing film 150, thereby ensuring black characteristics of thetransmission mode.

The pixel electrodes 117 at the transmission portions are disposedparallel with the common electrodes 124 to generate first transversalelectric fields (E1), and the pixel electrodes 117 at the reflectionportions are disposed above the reflection electrodes 120 to generatesecond transversal electric fields (E2).

That is, the liquid crystal display device of the present invention isdriven in a semi-transmission mode. When an external light source is notpresent, the liquid crystal display device is driven in a transmissionmode by the first transversal electric fields (E1) formed at thetransmission portions (T), and when an external light source is present,the liquid crystal display device is driven in a reflection mode by thesecond transversal electric fields (E2) formed at the reflectionportions (R).

Specifically, the TFTs are formed at the crossings of the gate and datalines 112 and 115, and control a voltage according to addressing signalsso that the voltage is applied or not applied to the pixel electrodes.Each of the TFTs comprises a gate electrode 112 a branched from the gateline 112, the gate insulating layer 113 laminated on the gate electrode112 a, a semiconductor layer 114 having an island shape formed bydepositing amorphous silicon (a-Si:H) on the gate electrode 112 a, andsource and drain electrodes 115 a and 115 b branched from the data line115 and formed on the semiconductor layer 114.

The reflection electrodes 120 are overlapped on the reflection potions(edges of the pixel regions) including the regions in which the gate anddata lines 112 and 115, and the TFTs are formed. The reflectionelectrodes 120 are formed at the reflection portions (R) and reflectexternal natural light, incident from the color filter array substrate121, towards the color filter array substrate 121, thereby displaying animage.

A Vcom voltage is applied to the reflection electrodes 120 so that thesecond transversal electric fields (E2), each generated between thereflection electrode 120 and the pixel electrode 117 above thereflection electrodes 120, thereby controlling the orientation of theliquid crystal when the liquid crystal display device is driven in thereflection mode. The passivation layer 118 made of an inorganicinsulating material is generated between the reflection electrodes 120and the pixel electrodes 117, thereby insulating the reflectionelectrodes 120 and the pixel electrodes 117 from each other.

The dimensions of the reflection electrodes 120 are varied according tothe ratio of the reflection portions (R) to the transmission portions(T). The reflection electrodes 120 are made of metal having a highreflectance, such as aluminum (Al), copper (Cu), and chrome (Cr).

The common electrodes 124 and the pixel electrodes 117 are disposed inparallel at the transmission portions so that the first transversalelectric fields (E1) are generated between the common electrodes 124 andthe pixel electrodes 117 and control the orientation of the liquidcrystal when the liquid crystal display device is driven in thetransmission mode. The common electrodes 124 and the pixel electrodes117 are insulated from each other by the passivation layer 118, andregions, each generated between the common electrode 124 and the pixelelectrode 117, becomes the transmission portions (T).

The common electrodes 124 are formed in the same layer as that of thereflection electrodes 120, as shown in FIG. 3, thereby receiving a Vcomsignal. Otherwise, reflection electrodes 120 are formed in a differentlayer from that of the common electrodes 124, as shown in FIG. 6,thereby receiving a Vcom signal from an external driving circuitconnected to the reflection electrodes 120.

In order to form the reflection and common electrodes 120 and 124 indifferent layers, as shown in FIG. 6, after common lines 125 and thecommon electrodes 124 are formed simultaneously with the formation ofthe gate lines 112, the reflection electrodes 120 are formed thereon.That is, the gate lines 112, the common lines 125 parallel with the gatelines 112, and the common electrodes 124 extended from the common lines125 are simultaneously formed on the TFT array substrate 111, aninsulating layer is formed thereon, and the reflection electrodes 120are formed by depositing metal having excellent reflectioncharacteristics on the insulating layer and patterning the depositedmetal layer. The reflection electrodes 120 overlap the common lines 125,thereby ensuring the dimensions of the reflection portions (R).

As shown in FIG. 3, the pixel electrodes 117 at the transmissionportions are disposed parallel with the common electrodes 124, and thepixel electrodes 117 at the reflection portions are disposed above thereflection electrodes 120. Otherwise, as shown in FIG. 5, the pixelelectrodes 117 may be additionally disposed above the reflectionelectrodes 120 above the gate lines 112. Thereby, the second transversalelectric fields, each caused due to the interaction between thereflection electrode 120 and the pixel electrode 117, are formed abovethe gate lines 112, thereby improving the efficiency of the reflectionmode.

That is, in addition to the pixel electrodes 117 disposed above thereflection electrodes 120 above the data lines 115, the pixel electrodes117 may be disposed above the reflection electrodes 120 above the gatelines 112. In this case, the pixel electrodes 117 on the TFT arraysubstrate 111 are disposed in one direction, thereby causing the liquidcrystal molecules in the reflection and transmission portions (R and T)to be arranged in the same orientation. All the pixel electrodes 117 ofone pixel region are integrated, and are connected to the drainelectrode 115 b of the corresponding TFT.

The in-plane switching mode liquid crystal display device has a dualcell gap structure. Here, the organic insulating layer 116 is formed atthe reflection portions (R), thereby causing the reflection portions (R)and the transmission portions (T) to have different liquid crystal cellgaps. Since the organic insulating layer 116 has the same thickness asthe liquid crystal cell gap of the reflection portions (R), the liquidcrystal cell gap (d2) of the reflection portions (R) and the liquidcrystal cell gap (d1) of the transmission portions (T) are in the ratioof 1:2.

Accordingly, the liquid crystal layer 131 at the reflection portions (R)exhibits a λ/4 phase delay effect, and the liquid crystal layer 131 atthe transmission portions (T) exhibits a λ/2 phase delay effect.Thereby, there is no phase difference of an image reaching the surfaceof a screen.

The organic insulating layer 116 is formed at the same positions asthose of the reflection electrodes 120, and is obtained by applying anorganic insulating material, such as Benzocyclobutene (BCB) or acrylicresin.

As described above, the orientation of the liquid crystal layer 131 atthe reflection portions (R), having the liquid crystal cell gap halfthat of the liquid crystal layer 131 at the transmission portions (T) bythe organic insulating layer 116, is determined by the reflectionelectrodes 120 and the pixel electrodes 117 so that the liquid crystaldisplay device is driven in the reflection mode, and the orientation ofthe liquid crystal layer 131 at the transmission portions (T) withoutthe organic insulating layer 116 is determined by the common electrodes124 and the pixel electrodes 117 so that the liquid crystal displaydevice is driven in the transmission mode.

Hereinafter, a method for fabricating the in-plane switching liquidcrystal display device of the present invention will be described.

FIGS. 7A to 7D are sectional views taken along line III-III′ of FIG. 3,illustrating a process for fabricating the liquid crystal display deviceof FIG. 3.

First, as shown in FIG. 7A, in order to prevent signal delay, aplurality of gate lines 112 and gate electrodes 112 a are formed bydepositing metal having a low resistance on the TFT array substrate 111and patterning the deposited metal. Then, the gate insulating layer 113is formed by depositing an inorganic insulating material, such assilicon oxide (SiOx) or silicon nitride (SiNx), on the overall surfaceof the TFT array substrate 111 including the gate lines 112 by plasmaenhanced chemical vapor deposition (PECVD).

Thereafter, the semiconductor layer 114 is formed on the gate insulatinglayer 113 over the gate electrodes 112 a by depositing amorphous silicon(a-Si:H) on the overall surface of the TFT array substrate 111 includingthe gate insulating layer 113 at a high temperature and patterning thedeposited amorphous silicon, and a plurality of data lines 115 and thesource and drain electrodes 115 a and 115 b are formed by depositingmetal having a low resistance on the overall surface of the TFT arraysubstrate 111 including the semiconductor layer 114 and patterning thedeposited metal.

The data lines 115 and the gate lines 112, which orthogonally cross eachother, define unit pixel regions. The source and drain electrodes 115 aand 115 b overlap the semiconductor layer 114. Thus, the gate electrodes112 a, the gate insulating layer 113, the semiconductor layer 114, thesource and drain electrodes 115 a and 115 b form TFTs.

The metal having a low resistance, which is used to form the gate lineand gate electrodes, the data line layer, is made of one selected fromthe group consisting of copper (Cu), aluminum (Al), Aluminum Neodymium(AlNd), molybdenum (Mo), chrome (Cr), titanium (Ti), tantalum (Ta), andmolybdenum-tungsten (MoW).

As shown in FIG. 7B, the organic insulating layer 116 is formed bycoating an organic insulating material, such as BCB or acrylic resin, onthe overall surface of the TFT array substrate 111 including the datalines 115, and patterning the coated organic insulating material so thatthe organic insulating material remains on the reflection portions. Theorganic insulating layer 116 is formed on the gate lines 112 and thedata lines 115 and the TFTs such that the drain electrodes 115 b of theTFTs are selectively exposed to the outside.

The organic insulating layer 116 is required to form the dual cell gapstructure of the liquid crystal layer. In order to set the ratio of theliquid crystal cell gaps of the reflection portions and the transmissionportions to 1:2, the organic insulating layer 116 has a thicknesscorresponding to the liquid cell gap of the liquid crystal layer at thereflection portions.

As shown in FIG. 7C, the reflection and common electrodes 120 and 124are simultaneously formed by depositing a metal having excellentreflectance on the TFT array substrate 111 and patterning the depositedmetal. The reflection electrodes 120 are formed on the organicinsulating layer 116 at the reflection portions, and the commonelectrodes are formed at the transmission portions.

The reflection electrodes 120 are integrally formed with the commonelectrodes so that a Vcom signal is transmitted from a driving circuitportion to the reflection electrodes 120, and are not connected to thedrain electrodes 115 b exposed from the organic insulating layer 116 sothat a pixel voltage is applied to the reflection electrodes 120.

On the other hand, as shown in FIG. 6, the reflection electrodes 120 andthe common electrodes 124 may be formed in different layers. The commonelectrodes 124 may be simultaneously formed with the gate lines 112, andthen the reflection electrodes 120 are formed on the gate insulatingfilm. Specifically, when the gate lines 112 are formed, the common lines125 parallel with the gate lines 112 and the common electrodes 124extended from the common lines 125 are simultaneously formed, the gateinsulating layer is formed thereon, and the reflection electrodes 120are formed at the reflection portions including the common lines 125 onthe insulating film. In this case, a Vcom signal is applied separatelyto the reflection electrodes 120 and the common electrodes 124.

As shown in FIG. 7D, the passivation layer 118 is formed on the TFTarray substrate 111 by depositing an inorganic insulating material, suchas silicon oxide (SiOx) or silicon nitride (SiNx), on the overallsurface of the TFT array substrate 111 including the reflectionelectrodes 120, and contact holes 119 are formed through the passivationlayer 118 so that the drain electrodes 115 b are exposed to the outsidethrough the contact holes 119.

Finally, the pixel electrodes 117, which are electrically connected tothe drain electrodes 115 b through the contact holes 119, are formed bydepositing a transparent conductive material, such as indium tin oxide(ITO) or indium zinc oxide (IZO), on the overall surface of the TFTarray substrate 111 including the passivation layer 118 and patterningthe deposited transparent conductive material. The pixel electrodes 117at the transmission portions are disposed parallel with the commonelectrodes 124, and the pixel electrodes 117 at the reflection portionsare disposed above the reflection electrodes 120.

Accordingly, the transversal electric fields, each generated between thecommon electrode 124 and the pixel electrode 117, are formed at thetransmission portions so that the liquid crystal display device isdriven in the transmission mode, and the transversal electric fields,each generated between the reflection electrode 120 and the pixelelectrode 117, are formed at the reflection portions so that the liquidcrystal display device is driven in the reflection mode.

For reference, as shown in FIG. 5, the transversal field may be formedby disposing the pixel electrodes 117 on the reflection electrodes abovethe gate lines 112, thereby improving the efficiency of the reflectionmode. The pixel electrodes 117 formed at each of the unit pixel regionsare integrally formed, are connected to the drain electrode 115 b, andare arranged in parallel in one direction, thereby causing liquidcrystal molecules to be arranged in the same orientation.

Thereafter, although not shown in the drawings, the color filter arraysubstrate is attached to the above-mentioned TFT array substrate suchthat the two substrates face each other, and the liquid crystal layer isinterposed between the two substrates, thereby completing thefabrication of the in-plane switching mode liquid crystal displaydevice. The color filter array substrate comprises black matrices formedat portions, which have unstable electric fields and cannot correctlycontrol liquid crystal, for preventing light leakage, and a color filterlayer formed between the black matrices for representing R (red), G(green), B (blue) colors. Since the reflection electrodes are formed atthe edges of the pixel regions where the black matrices are formed, thecolor filter array substrate need not comprise the black matrices.

The in-plane switching mode liquid crystal display device of the presentinvention further comprises orientation films formed on the innersurfaces of the TFT and color filter array substrates for settinginitial arrangement of liquid crystal molecules, polarizing films formedon the outer surfaces of the TFT and color filter array substrates forpolarizing light, and a compensating film interposed between the TFTarray substrate and the polarizing film for ensuring blackcharacteristics of the transmission portions. Although a compensatingfilm may be interposed between the color filter array substrate and thepolarizing film for performing the reflection mode, the liquid crystaldisplay device of the present invention need not comprise such acompensating film.

Hereinafter, with reference to FIGS. 8 to 10, an arrangement of anoptical system of the in-plane switching mode liquid crystal displaydevice of the present invention and an optical route of the opticalsystem will be described.

FIG. 8 is a schematic view of the optical system of the liquid crystaldisplay device of the present invention, FIG. 9 is a table illustratingthe variation in the polarized state of reflection portions of theliquid crystal display device of the present invention, and FIG. 10 is atable illustrating the variation in the polarized state of transmissionportions of the liquid crystal display device of the present invention.

The in-plane switching mode liquid crystal display device of the presentinvention is set to a normally black system by controlling polarizingoptical axes of the polarizing films, an optical axis of thecompensating film, and angles of directors of liquid crystal molecules.The liquid crystal cell gap structure of the liquid crystal layer 131 iscontrolled such that the liquid crystal layer at the reflection portionshas a phase difference of λ/4 and the liquid crystal layer at thetransmission portions has a phase difference of λ/2. A half wave plate(HWP) having a phase difference of λ/2 is used as the compensating film.

That is, as shown in FIG. 8, the upper polarizing film (hereinafter,referred to as “the upper POL”) and the lower polarizing film(hereinafter, referred to as “the lower POL”) are disposed such that thepolarizing optical axes of the upper and lower POLs are perpendicular toeach other, the initial orientation of liquid crystal molecules is at anangle of 45° between the upper and lower POLs, and the optical axis ofthe compensating film is disposed at an angle of 90° from the initialorientation of the liquid crystal molecules.

For example, when the polarizing optical axis of the upper POL is at anangle of about 0°, the polarizing optical axis of the upper POL is setto an angle of about 90°, the initial orientation of the liquid crystalmolecules is set to an angle of about 45°, and the optical axis of thecompensating film is set to an angle of about 135°.

When the liquid crystal layer is not driven, the liquid crystal layer atthe reflection portions (R) exhibiting a λ/4 phase delay effect servesas a quarter wave plate (QWP) changing linearly polarized light intocircularly polarized light or circularly polarized light into linearlypolarized light, and the liquid crystal layer at the transmissionportions (T) exhibiting a λ/2 phase delay effect serves as a half waveplate (HWP) changing the polarization of light in a symmetricaldirection with respect to the liquid crystal layer. When the liquidcrystal layer is driven, liquid crystal molecules are rotated at anangle of about −45° so that the angle of the orientation of the liquidcrystal molecules coincides with the angle of the polarizing opticalaxis of the upper POL.

Now, an optical route of external natural light applied to thereflection portions of the above-mentioned device will be described. Asshown in FIG. 9, when the liquid crystal layer is not driven (in an OFFstate), external natural light incident upon the upper POL passesthrough the liquid crystal layer (exhibiting the λ/4 phase delay effect)so that the external natural light is changed into circularly polarizedlight, and reaches the reflection electrodes, and the circularlypolarized light reflected by the reflection electrodes passes throughthe liquid crystal layer (exhibiting the λ/4 phase delay effect) againso that the circularly polarized light is changed into linearlypolarized light. Since the polarized light passes through the liquidcrystal layer exhibiting the λ/4 phase delay effect twice, the linearlypolarized light is rotated at an angle of about 90°. That is, since thelight is emitted in a direction at an angle of about 90° from thepolarizing optical axis of the upper POL, the light does not passthrough the upper POL, thereby implementing a black level.

On the other hand, when the liquid crystal layer is driven (in an ONstate), the liquid crystal molecules are rotated and located at the sameangle as the polarizing axis of the upper POL. Then, external naturallight incident upon the upper POL passes through the liquid crystallayer without change, and reaches the reflection electrodes, and thenatural light reflected by the reflection electrodes passes through theliquid crystal layer again without change of the optical axis, and isemitted in the same direction as the polarizing optical axis of theupper POL. Accordingly, the light finally passes through the upper POL,thereby implementing a white level.

An optical route of external natural light applied to the transmissionportions of the above-mentioned device will be described now. As shownin FIG. 10, when the liquid crystal layer is not driven (in an OFFstate), light incident from a lower backlight upon the lower POL passesthrough the compensating film (HWP, exhibiting the λ/2 phase delayeffect) so that the light is rotated at an angle of 90°, passes throughthe liquid crystal layer (exhibiting the λ/2 phase delay effect) so thatthe light is rotated again at an angle of about 90°, and is emitted inthe same direction as the polarizing optical axis of the lower POL.Accordingly, the light does not pass through the upper POL disposed atan angle of about 90° from the lower POL, thereby implementing a blacklevel.

On the other hand, when the liquid crystal layer is driven (in an ONstate), the liquid crystal molecules are rotated and disposed at thesame angle as the polarizing axis of the upper POL. Light incident fromthe lower backlight upon the lower POL passes through the compensatingfilm (HWP, exhibiting the λ/2 phase delay effect) so that the light isrotated at an angle of about 90°, and is emitted in the same directionas the polarizing optical axis of the upper POL. Thereafter, the lightpasses through the liquid crystal layer and the polarizing optical axisof the upper POL without change, thereby implementing a white level.

FIG. 11 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a fourth embodiment of the presentinvention, FIG. 12 is a sectional view taken along line IV-IV′ of FIG.11, and FIGS. 13A to 13D are sectional views taken along line V-V′ ofFIG. 11, illustrating a process for fabricating the liquid crystaldisplay device of FIG. 11.

FIG. 14 is a plan view of an in-plane switching mode liquid crystaldisplay device in accordance with a fifth embodiment of the presentinvention.

The in-plane switching mode liquid crystal display device in accordancewith other embodiments of the present invention has a single liquidcrystal cell gap structure regardless of the reflection portions (R)corresponding to the edges of the pixel regions and the transmissionportions (T) corresponding to the inner parts of the pixel regions.

As shown in FIGS. 11 and 12, a TFT array substrate 511 comprises gatelines 512 and data lines 515 orthogonally crossing each other fordefining unit pixel regions, a gate insulating layer 513 for insulatingthe gate and data lines 512 and 515 from each other, TFTs formed at thecrossings of the gate and data lines 512 and 515, an inorganicinsulating layer 516 formed on the overall surface of the TFT arraysubstrate 511 including the TFTs, reflection electrodes 520 formed onthe inorganic insulating layer 516 at the reflection portions, commonelectrodes 524 formed at the transmission portions, a passivation layer518 formed on the overall surface of the TFT array substrate 511including the reflection electrodes 520, and pixel electrodes 517 formedon the passivation layer 518 parallel with the common electrodes 524 forforming first transversal electric fields (E1) and formed above thereflection electrodes 520 for forming second transversal electric fields(E2).

A color filter array substrate 521 having black matrices 522 and a colorfilter layer 523 is attached to the TFT array substrate 511 such thatthe two substrates 521 and 511 face each other, and a liquid crystallayer 531 is interposed between the two substrates 521 and 511. Firstand second polarizing films 550 and 551 are respectively attached toouter surfaces of the two substrates 511 and 521. A compensating film560 is attached between the TFT array substrate 511 and the firstpolarizing film 550, thereby ensuring black characteristics of thetransmission mode.

The first transversal electric fields (E1), each generated between thecommon electrode 524 and the pixel electrode 517, control the liquidcrystal layer 531 in the transmission mode in which a backlight is usedas a light source, and the second transversal electric fields (E2), eachgenerated between the reflection electrode 520 and the pixel electrode517, control the liquid crystal layer 531 in the reflection mode inwhich external natural light is used as a light source. That is, theliquid crystal display device of the present invention can be driven inthe semi-transmission mode.

Since the inorganic insulating layer 516 having high permittivity isformed between the data lines 515 and the reflection electrodes 520,when the data lines 515 and the reflection electrodes 520 overlap witheach other, parasitic capacitance is generated therebetween, therebyexerting a negative influence on the quality of the screen. Accordingly,the reflection electrodes 520 do not overlap with the data lines 515,and are formed at both sides of the data lines 515.

The inorganic insulating layer 516 is made of an inorganic insulatingmaterial having permittivity of approximately 7.5, such as SiNx andSiOx, and has a thickness of about 1,500˜5,000 Å.

However, when an organic insulating layer 616 having low permittivity isformed between the data lines 515 and the reflection electrodes 520, asshown in FIG. 14, parasitic capacitance is not generated therebetween.Accordingly, in this case, the reflection electrodes 520 are formedabove the data lines 515 such that the reflection electrodes 520 overlapwith the data lines 515.

The organic insulating layer 616 is made of an organic insulatingmaterial having permittivity of 3.4, such as Benzocyclobuten (BCB) andacrylic resin, and has a thickness of about 3˜5 μm.

A Vcom voltage is applied to the reflection electrodes 520 so that thesecond transversal electric fields (E2) are generated between thereflection electrodes 520 and the pixel electrodes 517 formed above thereflection electrodes 520, thereby controlling the orientation of theliquid crystal in the reflection mode. The passivation layer 518 made ofan inorganic insulating material is formed between the reflectionelectrodes 520 and the pixel electrodes 517, thereby insulating thereflection electrodes 520 and the pixel electrodes 517 from each other.

The dimensions of the reflection electrodes 520 are varied according tothe ratio of the reflection portions (R) to the transmission portions(P). The reflection electrodes 520 are made of metal having highreflectance, such as aluminum (Al), copper (Cu), and chrome (Cr).

The common electrodes 524 and the pixel electrodes 517 are disposed inparallel at the transmission portions (T) so that the first transversalelectric fields (E1) are generated between the common electrodes 524 andthe pixel electrodes 517, thereby controlling the orientation of theliquid crystal in the transmission mode.

The common electrodes 524 are branched from common lines (not shown)formed in the same layer as that of the gate lines 512, thus receiving aVcom signal. Otherwise, the common electrodes 524 are formed in the samelayer as that of the reflection electrodes 520, thus receiving a Vcomsignal simultaneously with the reflection electrodes 520. When thecommon electrodes 524 are formed in a different layer from that of thereflection electrodes 520, the reflection electrodes 520 at the insideor the outside of an active region contact the common electrodes 524 sothat a Vcom signal is applied to the reflection electrodes 520, and areextended to overlap with the common lines (including the commonelectrodes 524), thereby additionally generating storage capacitance.

The pixel electrodes 517 formed above the reflection electrodes 520 andthe pixel electrodes 517 disposed parallel with the common electrode 524are integrally interconnected, and contact drain electrodes 515 b of theTFTs. The pixel electrodes 517, the reflection electrodes 520, and thecommon electrodes 524 are disposed in parallel, thereby generating thefirst and second transversal electric fields (E1 and E2) in the samedirection. Thus, the orientation of the liquid crystal molecules at thereflection portions (R) is equal to that of the liquid crystal layer 531at the transmission portions (T).

At this time, the pixel electrodes 517 are extended to overlap with thegate lines 512 or reflection electrodes 520, thereby forming storagecapacitors (Cst) by means of the gate lines 512, the pixel electrodes517, and the gate insulating layer 513 and the inorganic insulatinglayer 516, formed between the gate lines 512 and the pixel electrodes517. Storage capacitors are further formed by means of the reflectionelectrodes 520, the pixel electrodes 517, and the inorganic insulatinglayer 516, formed between the reflection electrodes 520 and the pixelelectrodes 517.

The above-mentioned in-plane switching mode liquid crystal displaydevice, which comprises the inorganic insulating layer or the organicinsulating layer having a designated stepwise structure between the datalines and the reflection electrodes and has a uniform liquid crystalcell gap structure, exhibits the same phase delay effect of the liquidcrystal layer at the reflection and transmission portions. In theembodiments of the present invention, the liquid crystal layer exhibitsa λ/4 phase delay effect.

Hereinafter, a method for fabricating the above-mentioned in-planeswitching liquid crystal display device will be described.

First, as shown in FIG. 13A, a plurality of gate lines 512 (in FIG. 11)and gate electrodes 512 a are formed on the TFT array substrate 511 bydepositing metal having a low resistance on the TFT array substrate 511and patterning the deposited metal. The gate insulating layer 513 isformed on the TFT array substrate 511 by depositing an inorganicinsulating material on the overall surface of the TFT array substrate511 including the gate electrodes 512 a.

A semiconductor layer 514 is formed on the gate insulating layer 513 onthe gate electrodes 512 a by depositing amorphous silicon (a-Si:H) onthe overall surface of the TFT array substrate 511 including the gateinsulating layer 513 at a high temperature and patterning the depositedamorphous silicon, and a plurality of the data lines 515 and the sourceand drain electrodes 515 a and 515 b are formed by depositing metalhaving a low resistance on the overall surface of the TFT arraysubstrate 511 including the semiconductor layer 514 and patterning thedeposited metal.

Here, the gate electrodes 512 a, the gate insulating layer 513, thesemiconductor layer 514, and the source and drain electrodes 515 a and515 b form TFT transistors.

As shown in FIG. 13B, the inorganic insulating layer 516 is formed bydepositing an inorganic insulating material, such as SiOx or SiNx, onthe overall surface of the TFT array substrate 511 including the drainelectrodes 515 b by PECVD.

Then, the reflection electrodes 520 and the common electrodes 524 (inFIG. 11) are simultaneously formed. By depositing metal having excellentreflectance on the TFT array substrate 511 and patterning the depositedmetal, the reflection electrodes 520 are formed at both sides of thedata lines 515 and the common electrodes 524 are formed parallel withthe long axes of the reflection electrodes 520. Regions of the TFT arraysubstrate 511 in which the reflection electrodes are disposed becomereflection regions, and other regions of the TFT array substrate 511become transmission portions.

On the other hand, when an organic insulating layer having lowpermittivity is formed on the overall surface of the TFT array substrate511 including the data lines 515, the reflection electrodes 520 may beformed on the TFT array substrate 511 such that the reflectionelectrodes 520 overlap the data lines 515.

As shown in FIG. 13C, the passivation layer 518 is formed by depositingan inorganic insulating material on the overall surface of the TFT arraysubstrate 511 including the reflection electrodes 520, and contact holes519 are formed through the insulating layer 516 so that the drainelectrodes 515 b are exposed to the outside through the contact holes519.

Finally, as shown in FIG. 13D, the pixel electrodes 517 electricallyconnected to the drain electrodes 515 b through the contact holes 519are formed on the TFT array substrate 511 by depositing a transparentconductive material, such as ITO or IZO, on the overall surface of theTFT array substrate 511 including the passivation layer 518 andpatterning the deposited transparent conductive material. The pixelelectrodes 517 at the transmission portions are disposed parallel withthe common electrodes 524, and the pixel electrodes 517 at thereflection portions are disposed above the reflection electrodes 520.

Accordingly, the first transversal electric fields (E1), each generatedbetween the common electrode 524 (in FIG. 11) and the pixel electrode517, are formed at the transmission portions, and the second transversalelectric fields (E2), each generated between the reflection electrode520 and the pixel electrode 517, are formed at the reflection portions.Here, since a Vcom signal is applied to the reflection electrodes 520,the first transversal fields (E1) are generated between the reflectionelectrodes 520 and the neighboring pixel electrodes 517.

Although not shown in the drawings, the color filter array substrate isattached to the TFT array substrate by means of the liquid crystal layerinterposed therebetween. The liquid crystal display device of thepresent invention further comprises orientation films formed on theinner surfaces of the two substrates for setting initial arrangement ofliquid crystal molecules, polarizing films formed on the outer surfacesof the two substrates for polarizing light, and a compensating filminterposed between the TFT array substrate and the polarizing film forensuring black characteristics of the transmission portions.

The in-plane switching mode liquid crystal display device of the presentinvention is set to a normally black system by controlling polarizingoptical axes of the polarizing films, an optical axis of thecompensating film, and angles of directors of liquid crystal molecules.The upper and lower POLs formed on the outer surfaces of the colorfilter and TFT array substrates are disposed such that the polarizingoptical axes of the upper and lower POLs are perpendicular to eachother. The liquid crystal cell gap structure of the liquid crystal layeris controlled such that the liquid crystal layer at the reflection andtransmission portions (R and T) has the same phase difference of λ/4,and the compensating film has the same phase difference of λ4.

Here, the initial orientation of liquid crystal molecules of the liquidcrystal layer is at an angle of 45° between the upper and lower POLs,and the optical axis of the compensating film is disposed at an angle of90° from the initial orientation of the liquid crystal molecules.

For reference, when the liquid crystal layer at the reflection portionsmeets the upper or lower polarizing films at an angle of about 45°, thereflection portions form black conditions in which the reflectance isminimized, and when the angle between the liquid crystal layer and theupper or lower polarizing films is deviated from the angle of about 45°,the reflectance of the reflection portions is changed.

When the compensating film and the liquid crystal layer at thetransmission portions have the same phase difference, the optical axesof the compensating film and the liquid crystal layer are perpendicularto each other, and the optical axes of the upper and lower polarizingfilms are perpendicular to each other, light does not pass through thetransmission portions. When the optical axis of the liquid crystal layeris rotated so that the optical axes of the compensating film and theliquid crystal layer are in parallel, the transmission portions havemaximal luminance. For the reason, the orientation films are rubbed sothat the orientation films and the pixel electrodes form an angle ofabout 0˜10°. For example, when the angle between the optical axes of thecompensating film and the liquid crystal layer at the transmissionportions is about 70°, the variation in the transmittance is about 88%,when the angle therebetween is about 80°, the variation in thetransmittance is about 97%, and when the angle therebetween is about90°, the variation in the transmittance is about 100%. Although theangle between the optical axes of the compensating film and the liquidcrystal layer at the transmission portions is less than about 90°, thedecrease in the luminance is not high. However, it is proper to designthe in-plane switching mode crystal display device according to theoptical rule.

An optical route of external natural light applied from the outside tothe above-mentioned in-plane switching mode liquid crystal displaydevice is similar or equal to that of the in-plane switching mode liquidcrystal display device of the first embodiment.

As described above, in the in-plane switching mode liquid crystaldisplay device of the present invention, which is driven in thesemi-transmission mode, a Vcom voltage is applied to the reflectionelectrodes of the reflection portions and a pixel voltage is applied tothe pixel electrodes disposed above the reflection electrodes at thereflection portions, thereby causing the liquid crystal layer to bedriven by the reflection electrodes.

As apparent from the above description, the in-plane switching modeliquid crystal display device and method for fabricating the same of thepresent invention exhibits several effects, as follows.

First, since a Vcom signal is applied to reflection electrodes formed atedges of pixel regions and pixel electrodes are additionally disposedabove the reflection electrodes, the liquid crystal display device ofthe present invention generates transversal electric fields at the edgesof the pixel regions, thereby allowing liquid crystal molecules to bearranged in a desired direction in a reflection mode.

Accordingly, the loss in transmittance at the reflection portions isreduced and reflectance at the reflection portions is improved.

Second, since the reflection electrodes are formed on gate lines as wellas data lines and the pixel electrodes are additionally disposed abovethe reflection electrodes, the liquid crystal display device of thepresent invention generates second transversal electric fields due tothe interaction between the reflection electrodes and the pixelelectrodes on the gate lines.

Accordingly, the efficiency of the liquid crystal display device of thepresent invention in the reflection mode is improved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. An in-plane switching mode liquid crystal display device comprising:gate lines and data lines orthogonally crossing each other on a firstsubstrate for defining pixel regions having reflection portions andtransmission portions; thin film transistors at the crossings of thegate lines and the data lines; common electrodes formed at thetransmission portions of the pixel regions; reflection electrodes formedat the reflection portions of the pixel regions; pixel electrodes formedparallel with the common electrodes at the transmission portions andformed above the reflection electrodes at the reflection portions; asecond substrate attached to the first substrate such that the first andsecond substrates face each other; a liquid crystal layer interposedbetween the first and second substrates; and first and second polarizingfilms respectively attached to outer surfaces of the first and secondsubstrates.
 2. The device of claim 1, wherein the transmission portionscorrespond to inner parts of the pixel regions and the reflectionportions correspond to edges of the pixel regions.
 3. The device ofclaim 1, wherein the common electrodes are integrally formed with thereflection electrodes in a same layer.
 4. The device of claim 1, whereinthe common electrodes are formed in a different layer from thereflection electrodes.
 5. The device of claim 4, wherein the commonelectrodes extend from common lines formed in a same layer as the gatelines.
 6. The device of claim 1, wherein the reflection electrodes areformed above the gate lines.
 7. The device of claim 1, wherein thereflection electrodes are formed above the data lines.
 8. The device ofclaim 1, wherein the reflection electrodes do not overlap the data linesand are formed at both sides of the data lines.
 9. The device of claim1, further comprising an organic insulating layer formed between thedata lines and the reflection electrodes.
 10. The device of claim 9,wherein the organic insulating layer is formed only at the reflectionportions.
 11. The device of claim 10, wherein the organic insulatinglayer has a thickness corresponding to a height of the liquid crystallayer above the reflection electrodes.
 12. The device of claim 10,wherein the liquid crystal layer at the reflection portions exhibits aλ/4 phase delay effect, and the liquid crystal layer at the transmissionportions exhibits a λ/2 phase delay effect.
 13. The device of claim 9,wherein the organic insulating layer is formed on an overall surface ofthe first substrate.
 14. The device of claim 13, wherein the liquidcrystal layer at the reflection portions and the transmission portionsexhibits a λ/4 phase delay effect.
 15. The device of claim 1, furthercomprising an inorganic insulating layer formed on an overall surface ofthe first substrate between the data lines and the reflectionelectrodes.
 16. The device of claim 15, wherein the liquid crystal layerat the reflection portions and the transmission portions exhibits a λ/4phase delay effect.
 17. The device of claim 15, wherein the reflectionelectrodes do not overlap the data lines and are formed at both sides ofthe data lines.
 18. The device of claim 1, further comprising acompensating film between the first substrate and the first polarizingfilm at the transmission portions.
 19. The device of claim 18, whereinthe compensating film exhibits a same phase delay effect as the liquidcrystal layer at the transmission portions, and has an optical axisperpendicular to an initial orientation of the liquid crystal layer. 20.The device of claim 1, wherein a polarizing optical axis of the firstand second polarizing films are perpendicular to each other.
 21. Thedevice of claim 1, further comprising orientation films respectivelyattached to inner surfaces of the first and second substrates, whereinthe orientation films are rubbed so that the orientation films and thepixel electrodes form an angle of about 0˜10°.
 22. The device of claim1, further comprising an insulating layer formed between the reflectionelectrodes and the pixel electrodes.
 23. The device of claim 1, wherein:first transversal electric fields, each of which is generated betweenthe common electrodes and the pixel electrodes, control the liquidcrystal layer in a transmission mode; and second transversal electricfields, each of which is generated between the reflection electrodes andthe pixel electrodes, control the liquid crystal layer in a reflectionmode.
 24. The device of claim 1, wherein the common electrodes and thepixel electrodes are disposed in parallel to each other.
 25. The deviceof claim 1, wherein the pixel electrodes overlap the gate lines orreflection electrodes to form a storage capacitance.
 26. A method forfabricating an in-plane switching mode liquid crystal display devicecomprising: forming gate lines on a first substrate; forming a gateinsulating layer on an overall surface of the first substrate includingthe gate lines; forming data lines crossing the gate lines and definingpixel regions that are divided into reflection portions and transmissionportions; forming thin film transistors at the crossings of the gatelines and the data lines; forming common electrodes at the transmissionportions of the pixel regions; forming reflection electrodes at thereflection portions of the pixel regions; forming a passivation layer onthe overall surface of the first substrate including the reflectionelectrodes; forming pixel electrodes on the passivation layer parallelwith the common electrodes and pixel electrodes overlapping thereflection electrodes; attaching a second substrate to the firstsubstrate such that the first and second substrates face each other, andforming a liquid crystal layer therebetween; and attaching first andsecond polarizing films, respectively, to outer surfaces of the firstand second substrates.
 27. The method of claim 26, wherein thetransmission portions correspond to inner parts of the pixel regions andthe reflection portions correspond to edges of the pixel regions. 28.The method of claim 26, wherein the reflection electrodes extend so asto overlap the gate lines.
 29. The method of claim 26, wherein thereflection electrodes extend so as to overlap with the data lines. 30.The method of claim 26, further comprising forming an organic insulatinglayer between the data lines and the reflection electrodes.
 31. Themethod of claim 30, wherein the organic insulating layer is made of BCBor acrylic resin.
 32. The method of claim 30, wherein the organicinsulating layer is formed only at the reflection portions, and has athickness equal to the liquid crystal layer, wherein a ratio of gaps ofthe liquid crystal layer at the reflection portions to the transmissionportions is 1:2.
 33. The method of claim 30, wherein the organicinsulating layer is formed on the overall surface of the firstsubstrate.
 34. The method of claim 26, further comprising forming aninorganic insulating layer between the data lines and the reflectionelectrodes.
 35. The method of claim 34, wherein the inorganic insulatinglayer is made of silicon nitride or silicon oxide.
 36. The method ofclaim 34, wherein the reflection electrodes do not overlap the datalines and are formed at both sides of the data lines.
 37. The method ofclaim 26, wherein the pixel electrodes are formed integrally in paralleland contact the thin film transistors.
 38. The method of claim 26,wherein the common electrodes are integrally formed with the reflectionelectrodes.
 39. The method of claim 26, wherein the common electrodesare formed in a different layer from the reflection electrodes.
 40. Themethod of claim 39, wherein the common electrodes extend from commonlines formed in a same layer as the gate lines.
 41. The method of claim39, wherein the reflection electrodes are formed to electrically connectto the common electrodes.
 42. The method of claim 26, wherein thereflection electrodes are made of a conductive material havingreflection characteristics.
 43. The method of claim 26, wherein thepixel electrodes are made of a transparent conductive material.
 44. Themethod of claim 26, further comprising attaching a compensating filmbetween the first substrate and the first polarizing film.
 45. Themethod of claim 44, wherein: the first and second polarizing films aredisposed such that polarizing optical axes thereof are perpendicular toeach other; an orientation of the liquid crystal layer initially has anangle of about 45° from the polarizing optical axis of the secondpolarizing film, and coincides with the polarizing optical axis when theliquid crystal layer is driven; and the compensating film is disposedsuch that the optical axis thereof meets the liquid crystal layer at anangle of about 90°.